1. Field of the Invention
The present invention relates to a fixing mechanism for a backlight module, and more particularly to a fixing mechanism for fixing an optical assembly of a backlight module and to a backlight module.
2. Description of the Prior Art
A liquid crystal display (LCD) panel has been widely applied to electronic products with growth potential, such as a monitor, a notebook computer, a digital camera and so on. After an LCD panel manufacturer produces an LCD panel, it is needed to first combine the LCD panel with a color filter, then seal the both together to be filled with liquid crystal, and next assemble them with a backlight module, a driving IC, a control circuit and so on to form an LCD module for being sold to a downstream manufacturer.
The backlight module is one of important components of an LCD. Because the liquid crystal molecule can not emit light, the function of the backlight module is to provide enough brightness and uniform light so that the LCD can normally display an image. The backlight module mainly consists of a light source, a light cover, a reflector sheet, a light guide plate, a diffusion sheet, a brightness enhancement film and an outer frame.
Generally, the backlight module may be divided into two modes of a side-light type backlight module and a direct-light type backlight module according to the position of the light source. Please refer to FIG. 1, which discloses a partial sectional view of a prior side-light type backlight module. The backlight module 90 comprises a back plate 91 having a side wall 911 and supporting a light guide plate 92. Optical films (group) 93 are placed on the light guide plate 92. And a plastic frame 94 covers an outer peripheral edge of the back plate 91 and secures the optical films 93 and the light guide plate 92 thereby forming the side-light type backlight module 90.
The main difference between the structures of the direct-light type backlight module and the side-light type backlight module is that: there is no the light guide plate 92 disposed on the back plate 91. The direct-light type backlight module and the side-light type backlight module are similar in the fixing mechanism of the optical films 93. Whether in the direct-light type backlight module or in the side-light type backlight module, the optical films 93 are provided for enhancing the brightness on the central portion of the backlight module 90 and the whole backlight uniformity. However, the base materials of the optical films 93 are mostly polyethylene terephthalate (PET), so the friction coefficient therebetween is small. If the optical films 93 don't be well fixed, they easily jump out. At present, the common way is to employ the plastic frame 94 shown in FIG. 1 to press the optical films 93. But the clearance is often created due to the hot-expansion and cold-shrinkage factor of the plastic material and the PET material, resulting in the optical films 93 not be well fixed.
Moreover, because of according with the narrow frame design of the LCD, the area of the optical films 93 pressed by the plastic frame 94 also must be reduced. Accordingly, the fixing effect by the plastic frame 94 fixing the optical films 93 becomes worse. Furthermore, the optical films 93 in the backlight module also can be fixed by adhering an adhesive tape. Namely, the optical films 93 adhere to the light guide plate 92 or the side wall 911 of the back plate 91. But because most of the adhesive tapes easily lose effectiveness when tested under high-temperature and high-humidity environments, the precision of this mode is bad and the labor cost is also higher.
Hence, it is needed to provide a fixing mechanism for a backlight module and a backlight module to solve the problem existed in the prior art.